Facebook, Inc.

Daniel Nota Peek

Philippe Vincent Ajoux

Dmitri Perelman

Neil Earnest Chao

A multi-shard database system receives a transaction including multiple actions directed to different shards of the database system. The database system creates a transaction record including a transaction identifier and a transaction status for the transaction in a transaction database. The database system then executes, in parallel, the multiple actions on the different shards by associating with each data item involved in the transaction a data structure that includes the transaction identifier and new data to be applied to the data item. The database system then updates the transaction status in the transaction record for the transaction from pending to completed when each of the multiple actions is successfully executed on the corresponding shard. Consistency is eventually implemented when the data structures associated with the data items involved in the transaction are evaluated. The evaluation of a data structure can be triggered by a read request or other events.

Providing eventual consistency for multi-shard transactions

Speculative processing of begin transaction database messages may include receiving a begin transaction message from a database client, transmitting an acknowledgement of the begin transaction message to the database client prior to forwarding the begin transaction message to the database server, forwarding the begin transaction message to the database server, and receiving an acknowledgement of the begin transaction message from the database server. In some implementations, the acknowledgement of the begin transaction message to the database client is transmitted substantially without delay after receiving the begin transaction message from the database client.

Speculative begin transaction

Processing repetitive database queries may include receiving a database query having a connection identifier, determining whether a queue for database queries contains an earlier database query matching the received database query, identifying the second database query as matching the first database query if the queue contains an earlier matching database query, receiving query results for the earlier matching database query from a database server, and forwarding query results to the clients associated with both database queries using corresponding connection identifiers.

Repetitive query recognition and processing

Speculative processing of authentication messages may include transmitting a first series of simultaneous messages to a database client, the first series of simultaneous messages including a handshake message and a first authentication acknowledgement message, receiving a second series of simultaneous messages from the database client, the second series of simultaneous messages including an authentication message and a database message, and transmitting a database acknowledgment message to the database client. In some implementations, the second series of simultaneous messages is received from the database client substantially without delay after the transmission of the first series of simultaneous messages.

Speculative database authentication

Processing switch database operations may include receiving a database selection message from a database client, transmitting an unconditional acknowledgement to the database client in response to the database selection message, accessing a database query from a queue of queries from the a database client where the database query includes a user identifier and a database identifier, determining whether a matching backend database connection exists, and if a matching backend database connection exists, forwarding the database query to the matching backend database connection. In some embodiments, a matching backend database connection may be a backend database connection having a user identifier equivalent to the user identifier of the database query, and a database identifier that is equivalent to the database identifier the database query.

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Sunnyvale, CA, United States of America

Daniel Nota Peek